The following relates to the millimeter or submillimeter, or equivalently extremely high frequency (EHF) to terahertz (THz), device characterization arts, millimeter to submillimeter (EHF to THz) device spectroscopy arts, millimeter or submillimeter (EHF or THz) device probe arts, and the like.
The International Telecommunication Union (ITU) designates the frequency range 0.3 THz to 3 THz (where 1 THz=1012 Hz) as terahertz radiation, terahertz waves, or tremendously high frequency radiation. The terahertz radiation range can alternatively be written as the wavelength range 1 mm to 0.1 mm (or 100 micron), and hence the terahertz radiation range is also called submillimeter radiation, and is in the 0.1 mm to 1 mm range. The frequency range 30-300 GHz frequency range (1-10 mm wavelength range) is known as the Extremely High Frequency (EHF) or millimeter band, sometimes abbreviated as the “mmW” band. Thus, mmW radiation is in the 1 mm to 10 mm range. Sensor, transceiver, spectroscopy and communications systems, and the like electronic and photonic systems for the THz and mmW bands are distinctly different in technology and science as compared to lower frequency bands of the electromagnetic spectrum. Much like the infrared and optical frequency bands are separately addressed due to the aforementioned technological and scientific differences, the mmW and THz bands are also distinct from the rest of the radio frequency spectrum.
Recent advances in novel THz devices that exploit ultrafast quantum mechanical transitions in semiconductor systems (such as tunneling, plasma waves and so forth) are enabling new sensors for the THz band. New devices, such as heterostructure backward diodes (HBDs), 2D electron gas (2DEG) field effect transistors (FETs), high electron mobility transistors (HEMTs), metal-insulator-insulator-metal (MIIM) junctions and quantum cascade structures can be produced with cutoff frequencies well beyond 1 THz. In order to minimize parasitics and enable ultrafast operation, these devices typically have dimensions in the micrometer to nanometer scale. Such high speed devices are typically characterized in the millimeter wave (mmW) regime by contact probes. However, for the sub-millimeter or THz bands such probes are not readily available. For example, focal plane array antennas feature very small details that do not allow direct probe contact for input impedance characterization. Alternatively, indirect impedance characterization methods have been developed in order to characterize THz antennas.